Please Add Resources for Low-Level System Design.

Created by: prasadgujar

Hello, @donnemartin Thanks for the great compilation for the system design resources but one important thing is missing from this as a great collection of resources is Low-Level Design resources. taking inspiration from the system design primer I created the low-level design primer which is similar to the system design primer. Please add the below resources for the low-level system design as well. Resources: https://github.com/prasadgujar/low-level-design-primer Thank you :)